Portable spa



FIG. 1 is a top plan view of the portable spa according to the present invention;

FIG. 2 is a right rear perspective view of the portable spa of FIG. 1; and,

FIG. 3 is a front perspective view of the portable spa of FIG. 1.

The broken line showing is for illustrative purposes only and forms no part of the claimed design. 

The ornamental design for a portable spa, as shown and described. 